1. Field of the Invention
This invention relates to an article especially adapted for connection on a printed circuit board, for displaying light indications of circuit diagnostic situations, and to a method of making such an article. Fault indicators for this purpose pose a number of special problems to the designer, in particular because of the unusual orientation of the illuminating display with respect to the mounting surface of the device. These indicators are normally mounted adjacent an edge of relatively large printed circuit boards, and are arranged so that when the equipment is opened for maintenance a technician can see the light display on those boards and at those locations that are symptomatic of particular faults. The smallest physical size compatible with reasonable ease in handling and initial assembly are important, so that the fault indicator does not require a spacing between boards which is greater than what would be required for cooling air or other components.
Because of the complexity of modern day printed circuit boards, it is also often desirable to be able to indicate the portion of the major circuit within which the fault has occured. This suggests the use of a plurality of such indicators on each printed circuit board, while at the same time space and handling considerations militate against the use of a large number of separately installed devices.
2. Description of the Prior Art
Single element side-viewed logic state or fault indicators have been made in a size suitable for use on a printed circuit board, for example, the Dialight series 555 devices. These units fulfill the requirements of extremely small size, and can be stacked along side each other on 0.100 inch centers to be compatible with common printed circuit hole coordinates. These units utilize miniature light emitting diodes whose front lens portions protrude through the front of the casing of the unit, so that they can be viewed from the front and also from a certain angle to each side. The requirements of miniature size with protruding lens, however, lead to a complex construction and assembly. These known units utilize housings molded as mating halves, which are held together by gluing or ultrasonic welding.